Azole Antifungal Agents To Treat the Human Pathogens Acanthamoeba castellanii and Acanthamoeba polyphaga through Inhibition of Sterol 14α-Demethylase (CYP51).

Abstract

In this study, we investigate the amebicidal activities of the pharmaceutical triazole CYP51 inhibitors fluconazole, itraconazole, and voriconazole against Acanthamoeba castellanii and Acanthamoeba polyphaga and assess their potential as therapeutic agents against Acanthamoeba infections in humans. Amebicidal activities of the triazoles were assessed by in vitro minimum inhibition concentration (MIC) determinations using trophozoites of A. castellanii and A. polyphaga. In addition, triazole effectiveness was assessed by ligand binding studies and inhibition of CYP51 activity of purified A. castellanii CYP51 (AcCYP51) that was heterologously expressed in Escherichia coli. Itraconazole and voriconazole bound tightly to AcCYP51 (dissociation constant [Kd] of 10 and 13 nM), whereas fluconazole bound weakly (Kd of 2,137 nM). Both itraconazole and voriconazole were confirmed to be strong inhibitors of AcCYP51 activity (50% inhibitory concentrations [IC50] of 0.23 and 0.39 μM), whereas inhibition by fluconazole was weak (IC50, 30 μM). However, itraconazole was 8- to 16-fold less effective (MIC, 16 mg/liter) at inhibiting A. polyphaga and A. castellanii cell proliferation than voriconazole (MIC, 1 to 2 mg/liter), while fluconazole did not inhibit Acanthamoeba cell division (MIC, >64 mg/liter) in vitro. Voriconazole was an effective inhibitor of trophozoite proliferation for A. castellanii and A. polyphaga; therefore, it should be evaluated in trials versus itraconazole for controlling Acanthamoeba infections.

• Authors: David C Lamb, Andrew G S Warrilow, Nicola J Rolley, Josie E Parker, W David Nes, Stephen N Smith, Diane E Kelly, Steven L Kelly
• Journal: Antimicrobial agents and chemotherapy (Antimicrob Agents Chemother) Vol. 59 Issue 8 Pg. 4707-13 (Aug 2015) ISSN: 1098-6596 [Electronic] United States
• PMID: 26014948 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Chemical References

• 14-alpha Demethylase Inhibitors
• Amebicides
• Antifungal Agents
• Azoles
• Triazoles
• Itraconazole
• Fluconazole
• Sterol 14-Demethylase
• Voriconazole

Topics

• 14-alpha Demethylase Inhibitors (pharmacology)
• Acanthamoeba castellanii (drug effects, metabolism)
• Amebiasis (drug therapy, microbiology)
• Amebicides (pharmacology)
• Antifungal Agents (pharmacology)
• Azoles (pharmacology)
• Cell Proliferation (drug effects)
• Fluconazole (pharmacology)
• Humans
• Itraconazole (pharmacology)
• Microbial Sensitivity Tests (methods)
• Sterol 14-Demethylase (metabolism)
• Triazoles (pharmacology)
• Voriconazole (metabolism)